Conference Highlights

Mark Willcox, BSc, PhD is a professor at the School of Optometry and Vision Science at the University of New South Wales. He specialises in the field of eye health, particularly the areas of ocular inflammation and microbiology.

Download the poster, which was originally shared at the American Academy of Optometry’s annual meeting, 2011.

Effect of a MPDS containing Polyquaternium-­1 and Alexidine dihydrochloride on contamination of contact lens cases

PURPOSE: Lack of maintenance of contact lens case hygiene has been shown in many epidemiology studies to be associated with increased risk of developing microbial keratitis. The aim of this study was to examine the colonisation of contact lens cases and types of microbes colonising cases during use of a multipurpose disinfecting solution (MPDS) containing Polyquaternium-1 and Alexidine dihydrochloride (RevitaLens OcuTec®; PQ/Alexidine).

METHODS: 120 subjects were enrolled in a trial to examine the contamination of contact lens cases when using 3 different silicone hydrogel contact lenses (lotrafilcon A, balafilcon A, or comfilcon A) and PQ/Alexidine. Cases (approximately 70 for each lens type) were collected after 1 month of use and cultured, using standard techniques, to enumerate the types of microbes within the lens case. The frequency of contamination of cases was calculated. These data were then compared to previously published data of other MPDS/contact lens combinations.

RESULTS: The rate of contamination was not affected by the type of contact lens worn. The rate of contamination of cases by Gram-positive bacteria was similar regardless of lens or MPDS type (71-84%). Contamination of cases by Gram-negative bacteria was significantly less for PQ/Alexidine (5%; p<0.01) compared to cases in which one type of polyhexanide (29%) or PQ/ALDOX MPDS (45%) had been used. In particular, the PQ/Alexidine cases were much less frequently colonised by Delftia acidovorans (5%), Stenotrophomonas maltophilia (4%), and Achromobacter sp. (2%) than cases with one type of PQ/ALDOX MPDS (26%; 14%; 10%). The fungal contamination of cases with PQ/Alexidine were significantly less frequently colonised with fungi (10%) than those with one type of polyhexanide MPDS (20%).

CONCLUSIONS: The MPDS containing PQ/Alexidine was able to significantly reduce the frequency of contamination of contact lenses cases, in particular by Gram-negative bacteria or fungi, compared to use of other MPDS.